Answer:
Hypersensitivity is also known as intolerance which is defines as an unwanted reactions due to changes or interference with immune system for example allergies and autoimmunity. Hypersensitivity is the reaction of immune system that can be harmful and weakens once body.
Allergy is kind of hypersensitive reaction which is having fast response within few minutes rather than hours or days. In the case of allergies free antigens cross link with IgE on mast cells and basophils and releases vasoactive biomolecules. Few example of Allergies are anaphylaxis and asthma.
Autoimmune disorders are also a kind of hypersensitive reaction which occurs when body's immune system attacks own body cells mistakenly. few examples are Type 1 diabetes, Rheumatoid arthritis (RA), and Multiple sclerosis.
Semen contains all of the following, EXCEPT
A. Fructose
B. Mucus
C. Clotting enzyme
D. Substances to lower the pH of the uterine environment
E. An active cot-dissolving enzyme
Semen does not contain substances to lower the pH of the uterine environment.
Explanation:The correct answer is D. Substances to lower the pH of the uterine environment.
Semen is the fluid that contains sperm, which is released during ejaculation. It contains various components that help sperm in their journey to fertilize an egg. These components include fructose (a sugar that provides energy for sperm), mucus (which helps with the motility of sperm), clotting enzymes (to prevent semen from leaking out of the vagina), and an active cot-dissolving enzyme (to break down the mucus in the cervix).
However, semen does not contain substances to lower the pH of the uterine environment. This is because the female reproductive tract naturally provides an optimal pH for sperm survival without the need for additional substances in semen.
Learn more about Semen composition here:https://brainly.com/question/31867736
People who misuse or overuse antibiotics may become resistant to them.
a. True
b. False
Answer:
True.
Explanation:
Antibiotics may be defined as the chemicals that are required to stop the growth and kill the other living organism. These antibiotics have been developed against bacteria, fungi and microorganisms.
The excess use of the antibiotics leads to the development of the resistant strain against that particular antibiotic. People should not overuse or misuse the antibiotics as they may become resistant and antibiotics will not effect the pathogens of that individual organism.
Thus, the correct answer is option (a).
Functional Magnetic Resonance Imaging is a tool that has been very useful in identifying what parts of the brain do what. Scientists can have a person perform some particular activity and then look for active areas in the brain. How does fMRI work?
A. It takes a picture of the inside of the brain according to electricity levels. The more electrical current in the area, the more active it is.
B. It takes a picture of the inside of the brain according to blood flow. More blood flow indicates more activity in that area.
C. It takes images of thin layers of the brain and the more electrical activity in a layer, the more magnetic it is and this shows up in fMRI.
D. Electrodes attached to the skull can trigger activity in particular brain areas which then trigger a person to perform certain behaviors.
E. It takes a picture of the brain according to oxygen levels. More oxygen in an area indicates more activity in that area.
Answer:
E. It takes a picture of the brain according to oxygen levels. More oxygen in an area indicates more activity in that area.
Explanation:
Haemoglobin is diamagnetic when oxygenated but paramagnetic when deoxygenated. This distinction in magnetic characteristics leads to tiny variations in the blood MR signal. Since blood oxygenation differs, these variations can be used to identify brain activity depending on the concentrations of neural activity.
Complementary base pairing in DNA means that DNA is easy to copy. How does this work?
A. DNA isn't very easy to copy, but there's no need to do that, so it doesn't matter.
B. The base pairs that make up the center of the DNA molecule will only match with identical copies of themselves A:A, C:C, etc.
C. The base pairs that make up the center of the DNA molecule will only match up A with T or C with G.
D. It doesn't work very well, so many mistakes are made when DNA gets copied as cells divide.
E. The base pairs that make up the center of the DNA molecule match other DNA molecules perfectly.
Answer:
The correct answer is option C.
Explanation:
On the basis of Chargaff's rule, adenine always base pairs with thymine, and guanine always base pairs with cytosine. This rule is also called complementary base pairing. By following this rule, the DNA polymerase can produce the new strand of DNA easily.
It utilizes the old strand of DNA as a template and produces the new one by opting for the accurate nucleotide on the basis of the template strand. Thus, the correct answer is option C, that is, the base pairs, which make up the center of the molecule of DNA will only match up C with G and A with T.
When mutations exhibit complementation this means the mutations are located:
a. in the same gene
b. in the different genes
c. in between genes
d. in non-coding DNA
e. in introns
Answer:
The correct option is: b. in the different genes
Explanation:
In an organism, complementation is observed when the two strains with the different homozygous recessive mutations are mated or crossed to produce an offspring having wild-type phenotype.
Complementation is observed when the mutations are present in different genes.
Therefore, mutations are said to be complementary, if they are present in different genes.
A common type of DNA damage from UV light results in:
a. bulky adducts
b. cross linked complementary strands
c. intrastrand crosslinks
d. free radicals
Answer:
C
Explanation:
The damage to DNA usually occurs where there are two consecutive thymine nucleotides on a DNA strand. The energy from the UV light causes the two dimers to form a cyclobutane pyrimidine structure. Proofreading and repair mechanism of DNA find it difficult to repair this kind of damage on DNA. During replication, therefore, DNA polymerase is unable to replicate this region hence leading to a mutation on the replicated strand at this local point.
What are: endocrine? Paracrine? Autocrine?
Answer:
Endocrine :
Endocrine cells may be defined as the cells that helps in the cell signalling in which the cells are located far apart. The product can shows slow effect but long lasting effect.
Paracrine:
Paracrine cells may be defined as the cells that are involved in the paracrine signalling. They acts on the cells that are located close to each other and generates quick response in body.
Autocrine :
Autocrine cells that are involved in the autocrine signalling affect their own cells. The target and signalling cells are same in autocrine. The pain sensations of the body are also regulated by autocrine signalling.
Final answer:
Endocrine, paracrine, and autocrine are types of cell signaling. Endocrine signaling travels long distances through bodily fluids, paracrine signaling acts locally between neighboring cells, and autocrine signaling occurs when a cell responds to its own signals.
Explanation:
In multicellular organisms, cells communicate through different types of signaling. The three main types are endocrine, paracrine, and autocrine signaling, each differing primarily in the distance the signal travels to reach the target cell.
Endocrine signaling involves hormones secreted into the extracellular fluid that then diffuse into the blood or lymph to travel to distant cells throughout the body. An example of endocrine signaling is the secretion of hormones by the pituitary gland.
Paracrine signaling involves signals, or paracrine factors, that act locally between cells that are close together. These signals move by diffusion through the extracellular matrix and are generally quickly degraded or removed to maintain localized effects. Histamine, responsible for the immune response in asthma, is an example of a paracrine signal.
Autocrine signaling occurs when a cell responds to signals it releases itself, with interleukin-1 (IL-1) being an instance of an autocrine involved in inflammatory responses. Autocrine signaling can also influence nearby similar cells and plays a key role in the early developmental processes and programmed cell death.
Blanching works to keep vegetables crisp and green when cooked because
a. PPOs are denatured at high temperature
b. Acids keep colors bright
c. Bases keep vegetables crisp
d. Ice water reverses Maillard reactions
Answer:
a. PPOs are denatured at high temperature
Explanation:
Polyphenol oxidase, PPO, is one of the most studied enzymes in the food industry as it is responsible for enzymatic browning reactions in fruits and vegetables. One of the reasons why its study is important is because commercially it is undesirable, since it modifies the sensory, nutritional and in general quality properties that impair the commercialization of a product.
The importance of controlling polyphenol oxidase is that it largely determines the quality and economic value of fruits and vegetables harvested, stored and processed. Bruising, chopping and other mechanical procedures damage the walls of fruits and vegetables which allows oxygen to penetrate, resulting in darkening or enzymatic browning reactions.
Enzymatic browning can be controlled through the use of chemical and physical methods, often used in combination. The commonly used physical methods are the reduction of temperature, oxygen and the use of modified atmospheres or coating films. The use of chemical methods will depend on what you want to inhibit, be it the enzyme, the substrate (oxygen or phenolic compounds) or the products.
Organisms that can't live in the presence of oxygen are called facultative anaerobes.
a. True
b. False
Answer:
False
Explanation:
Facultative anaerobes are organisms that can grow in both the presence or absence of oxygen.
Organism that suffer a poisonous reaction or that can't live in the presence of oxygen are called obligate anaerobes.
What is homeostasis? help me to understand homeostasis ?
Answer:
Explanation:
The mechanism in which internal conditions of the body are properly maintained and regulated.
Mutation is a random and non-adaptive process. This was first proven by:
a. Lysenko and Lamarck, using the removal of mouse tails as an environmental stress.
b. Joshua and Esther Lederberg, using the removal of mouse tails as an environmental stress.
c. Lysenko and Lamarck, using replica plated E. coli and streptomycin as an environmental stress.
d. Joshua and Esther Lederberg, using replica-plated E. coli and streptomycin as an environmental stress
e. Mutation is not a random, non-adaptive process
Answer:
Option (d).
Explanation:
Mutation may be defined as the sudden, heritable change in the nucleotide sequence of the organism. Mutation may occur due to the errors in DNA replication or may occurs due to the mutagens.
Joshua and Lederberg experiment explains that mutation is the non adaptive and random process that occur in the organism. He used the replica plating of E.coli and grows them on streptomycin drug. The bacteria was grown on the the primary plate and they are transferred to the secondary plate with streptomycin drug in the growth environment. The resistant strain of bacteria grows in the streptomycin environment.The pattern of bacteria growth on the plate explained that mutation occurs randomly and it is a non adaptive process.
Thus, the correct answer is option (d).
Differentiate between parental ditype (PD), non-parental ditype (NPD), and tetratype (T).
Answer:
Parental ditype (PD):
Parental ditype may be defined as the teterad type of the ascus that contains two different genotypes. These genotypes are both of the parental type. These are non recombinant ascospores.
Non-parental ditype (NPD):
Non-parental ditype may be defined as the ascus spores that do not resemble with the parent genotype. These tetrad type are the recombinant type of the ascus.
Tetratype:
Tetratype are the spores that contains the four different genotypes. The two genotypes are the parental type and two are recombinant type. The tetratype indicates the single cross overs.
Final answer:
Parental ditype (PD), non-parental ditype (NPD), and tetratype (T) are three types of offspring resulting from a genetic cross. PD offspring exhibit the same allelic combination as their parents, NPD offspring have a different allele combination due to homologous recombination, and T offspring have both parental and non-parental alleles indicating a crossover event.
Explanation:
In genetics, parental ditype (PD), non-parental ditype (NPD), and tetratype (T) are three types of offspring resulting from a genetic cross. These terms are used in the context of linked genes and recombination during meiosis.
Parental ditype (PD) refers to offspring that exhibit the same allelic combination as their parents. Non-parental ditype (NPD) refers to progeny that exhibit a different allele combination compared to their parents due to homologous recombination. Lastly, tetratype (T) progeny exhibit both parental and non-parental alleles, indicating a crossover event occurred during meiosis.
A human cell containing 22 autosomes and a Y chromosome is
a. a sperm.
b. an egg
c. a zygote.
d. a somatic cell of a male.
The correct answer is A. A sperm
Explanation:
Sperms are a type of reproductive cells that are essential for sexual reproduction. Sperms are male reproductive cells different from eggs that are female cells. Additionally, these can have flagella that allow them to move to reach the egg or be non-motile. In the case of human sperms, these have a flagella and also they contain 23 chromosomes; additionally, in this there is 1 allosome chromosome that defines sex and in males and therefore sperms can be either X or and 22 autosomes that refer to chromosomes not related to sex, this is also particular from sperms as eggs in humans can only have an X allosome. According to this, it is a sperm the cell that contains 22 autosomes and a Y chromosome.
You discover a new species and are given the task of describing and classifying it. Upon closer examination, you find that it has a single duct for reproductive, excretory, and defecatory material as well as a lack of true nipples. Which group are you sure this species does not belong to?
a. Mammalia
b. Metatheria
c. Prototheria
d. Synapsida
Answer:
a. Mammalia
Explanation:
Mammalia are the class species that have distinct systems and separate ducts for different activities like reproduction, excretory, and defecatory and moreover they have nipples to feed their young ones.
So, the above species which has a single duct for reproductive, excretory, and defecatory material as well as a lack of true nipples does not belong to Mammalia
During bacterial transformation, DNA that enters a cell is not an intact chromosome; instead it consists of randomly generated fragments of chromosomal DNA. In a transformation where the donor DNA was from a bacterial strain that was a+ b+ c+ and the recipient was a b c, 55% of the cells that became a+ were also transformed to c+ But only 2% of the a+ cells were b+. Is gene b or c closer to gene a?
Answer:
Gene c is closer to a.
Explanation:
The process by which the bacteria take up the genetic material which is foreign from the environment is called as bacterial transformation and it is a type of horizontal gene transfer. When during transformation there is a simultaneous transfer of two or more genes then such type of transformation called co-transformation.According to the question, there is co-transformation occurring for both the genes a and b as well as for a and c, however, the frequency of cotransformation of a and c is higher (55%) than a and b (2%).A higher frequency of co-transformation indicates that the two genes are located more closely on the chromosome and hence, are usually transferred together, thus a and c are much closer as compared to a and b.Proteins are broken down into ___________ by the enzyme ____________
Answer: Proteins are broken down into amino acids by protease enzymes.
Explanation:
Protein is an essential nutrients which is needed for growth and development. Protein is the major constituent of hormones, enzymes, eyes, muscles e.t.c.
The protein sources are eggs,beans,meats, milk e.t.c.
Protein digestion start in the stomach. Once protein consume get to the intestine, hydrochloric acid and protease enzymes breakdown protein into amino acids.The Amino acids are linked together by peptides bond. The perform this by cleaving to the peptides bond within the protein by a process called hydrolysis.
Categorize allele interactions as completely dominant, incompletely dominant, or codominant.
Answer:
Explanation:
Gregor Mendel showed his inheritance character in the garden pea plant. According to him, there are 2 alleles which are inheritable - dominant allele and recessive allele. The dominant allele is always dominant over the recessive one which is known as the complete dominance. When the offsprings have both recessive alleles it will show its character.
There are other characters present besides dominant and recessive. Such characters are known as Mendelian deviation as it does not obey Mendel's law of inheritance. e.g. codominance, incomplete dominance.
In codominance alleles, characters are blended and a new character has seen in the next generation. This new character is neither dominant not recessive, it is an intermediate character between the 2 characters.
e.g When the white and red flowers crossed pink flowers are formed along with red and white.
In the case of codominance, both alleles express their characters. Such phenotypic characters are known as codominance because both alleles are expressed in the offsprings.
e.g. When the red and white flower plants crossed the offspring flowers are red with white spots or the white with red spots.
Extrapyramidal effect of metoclopramide.
Answer:
Metoclopramide is a drug widely used for its antiemetic effect (that is, used for the symptomatic treatment of nausea and vomiting). Its adverse reactions are varied, affecting even the central nervous system, causing extrapyramidal syndromes.
Explanation:
Due to the antidopaminergic action of metoclopramide. Signs and symptoms can range from spasms of the muscles of the face, neck or tongue, motor agitation and tremor, acatisia (feeling restless and in need of constant movement) and acute dystonic reactions. Extrapyramidal syndrome is transient and disappears after eliminating or decreasing the dose of metoclopramide.
Metoclopramide is a drug that can be administered intravenously. Its administration can be in bolus or by a continuous infusion. Is there any method of choice to prevent or reduce the occurrence of pyramidal syndromes?
A recent systematic review concluded that, compared with bolus administration, continuous intravenous infusion of metoclopramide reduced the occurrence of extrapyramidal side effects.
With this gesture we can perform quality care and try to avoid side effects to our patients.
Explain how the exon/intron structure of genes contributes to the generation of new gene functions during evolution.
Answer:
The exons may be defined as the coding region of the RNA that codes for the particular amino acid. The introns are the non coding region of RNA and must be removed in the final RNA product.
Exon shuffling result in the formation of new gene. The alteration of the exon and intron structure leads to the new gene function in evolution. The genes that are favored and conserved in the evolution perform new gene function. The genes that are selected against are deleted during the evolution.
The exon/intron structure in genes facilitates the evolution of new functions through exon shuffling, alternative splicing, and gene duplication, significantly contributing to genetic diversity and adaptability.
Explanation:The exon/intron structure of genes is pivotal in the evolution of new gene functions. Introns, which are non-coding sequences, serve as a buffer against deleterious mutations, and through unequal recombination during meiosis, they can lead to gene duplication and exon shuffling. This occurrence can result in new proteins with additional structural domains and functions, contributing to genetic diversity and evolutionary progress.
Exon shuffling is a mechanism by which exons can be mixed and matched between genes, potentially creating proteins that carry out new functions. Additionally, introns and their associated sequences play a crucial role in alternative splicing, which allows for the production of multiple protein variants from a single gene, further increasing the potential for diversity and adaptability.
Gene duplication, which can occur due to non-homologous recombination facilitated by introns, allows one gene copy to accumulate mutations while the other maintains its original function. This duplicated gene can then evolve over time, adding to the pool of selectable DNA sequences and leading to an increase in species diversity and evolutionary innovation.
How many different DNA strands composed of 100 nucleotides could possibly exist?
Answer: There are 4¹⁰⁰ possible strands, approximately 1.61x10⁶⁰
Explanation:
This is a combinatorics problem. Each nucleotide has the possibility of being one of the four common nucleotides, adenine (A), guanine (G), thymine (T) and cytosine (C).
If the strand would be 1 nucleotide long, the possibilities would be 4, one for each possible nucleotide. If the strand would be 2 nucleotides long, for each nucleotide on the first position there would be four possible nucleotides on the second position, giving 4x4=4²=16 possible strands.
For 3 nucleotides long you have 4 possible nucleotides for each of the 2-nucleotide-long strands, 4x4x4=4²=64 possible strands. Following that pattern, for a 100 nucleotide long DNA strand, there would be 4x4x...x4x4=4¹⁰⁰ possible strands.
Select examples of energy changing forms. Select the THREE answers that are correct.
(A) From a high perch, a raptor dives toward its prey.
(B) An animal has stores of lipids in its fatty tissues.
(C) A green plant absorbs light to make sugar molecules.
(D) A seed remains dormant for an extended period.
(E) A human jogs down the street for exercise.
Final answer:
Examples of energy changing forms include a raptor converting potential to kinetic energy during a dive, a green plant transforming solar energy into chemical energy via photosynthesis, and a human converting chemical energy into kinetic energy while jogging.
Explanation:
Energy transformations are fundamental to biological processes and occur when energy changes from one form to another. Three examples of energy changing forms include:
(A) From a high perch, a raptor dives toward its prey: Potential energy stored due to the raptor's high position is transformed into kinetic energy as it dives towards its prey.(C) A green plant absorbs light to make sugar molecules: Solar energy is captured by photosynthetic organisms and converted into chemical energy in the form of glucose during the process of photosynthesis.(E) A human jogs down the street for exercise: Chemical energy stored in the body's molecules is converted into kinetic energy during physical activity.These instances illustrate how diverse organisms harness and convert energy to fuel their life functions, a concept centrally important to understanding biology.
Describe the key chromosome behaviors during mitosis.
Answer:
Explanation:
During mitosis, the chromosomes are distributed equally in the resulting chromosome. The chromosome number was doubled in the S phase of the interphase and the cell is ready for mitosis. The chromosomes are more condensed and twisted in prophase. It is also double in length. During the metaphase, the chromosomes are arranged in the metaphase plate. The microtubules from the centriole attach to the centromere of each chromosome and pull them towards the pole.
Thus each chromatid pulls apart and migrates towards the poles. The nuclear membrane and nucleus disappear during mitosis. At the end of telophase, the daughter cells contain an equal number of chromatids as in the parent cell.
Sometimes the microtubules of centrioles do not function properly and fail to pull the chromosomes equally to the cells. Thus one of the daughter cells contains more chromosomes and another fewer chromosomes. This occurs in anaphase. This results in the non-disjunction of chromosomes.
Sometimes centromere splits transversely instead of longitudinal division. This results in the formation of 2 daughter chromosomes of unequal length. This is called the isochromosomes.
The number of chromosomes distributed in the daughter cells results in a normal cell or any genetic disorder. The main function of mitosis to produce daughter cells having an equal number of chromosomes present in the parent cell.
How is the circulatory system controlled (i.e. hormonally, neurally)?
Answer:
Neurally
Explanation:
Cardiac regulation is controlled neurally. The nervous systems receive signals regarding the condition of the circulatory system. Different receptors receive different type of signals. For example, the baroreceptors, receive information about the blood pressure, the chemoreceptors sends and codify information about the CO2, O2 and PH concentration in the bloodstream.
All of these signals are processed and analyzed by a group of neurons in the spinal bulb in the brain. This particular region of the brain, produces signals that travel trough neurons until the nerve supply of the heart and the smooth muscles (of veins and arterioles) to control the blood pressure and cardiac output.
"The circulatory system is controlled through both hormonal and neural mechanisms.
Neurally, the circulatory system is regulated by the autonomic nervous system (ANS), which includes the sympathetic and parasympathetic branches. The sympathetic nervous system, when activated, increases heart rate, cardiac output, and the force of cardiac muscle contractions, thereby increasing blood pressure. This response is part of the ""fight or flight"" reaction. Conversely, the parasympathetic nervous system decreases heart rate and promotes relaxation, which is part of the ""rest and digest"" response.
Hormonally, several key hormones play a role in regulating the circulatory system:
1. Epinephrine and Norepinephrine: Released by the adrenal medulla, these hormones increase heart rate and the force of cardiac contractions, similar to the sympathetic nervous system's effects.
2. Atrial Natriuretic Peptide (ANP): Secreted by the atria of the heart in response to stretching due to increased blood volume, ANP promotes excretion of sodium and water by the kidneys, which in turn reduces blood volume and pressure.
3. Renin-Angiotensin-Aldosterone System (RAAS): When blood pressure drops, the kidneys release renin, which leads to the production of angiotensin II. Angiotensin II is a potent vasoconstrictor that increases blood pressure. It also stimulates the release of aldosterone from the adrenal cortex, which promotes sodium and water retention by the kidneys, further increasing blood volume and pressure.
4. Antidiuretic Hormone (ADH): Also known as vasopressin, ADH is released by the posterior pituitary gland in response to increased plasma osmolality or decreased blood volume. ADH increases water reabsorption in the kidneys, which increases blood volume and pressure.
5. Endothelins: These are a group of peptides produced by the endothelial cells lining the blood vessels. They are among the most potent vasoconstrictors known and play a role in regulating vascular tone and blood pressure.
These hormonal and neural controls work in concert to maintain homeostasis in the circulatory system, ensuring that blood flow and pressure are adjusted according to the body's changing needs."
In a hemoglobin variant known as hemoglobin Kansas, an Asparaginein
the beta chain is replaced by a Threonine. This results in
thedisruption of a hydrogen bond that normally stabilizes the
R-stateof hemoglobin. Which statement is FALSE regarding the effect
thisamino acid change has on the ability of hemoglobin Kansas to
bindoxygen?
a. Inhemoglobin Kansas, there is an increase in the amount of
R-stateand a decrease in the amount of T-state.
b. In hemoglobinKansas, there is a decrease in the amount of
R-state and anincrease in the amount of T-state.
c. The R-state inhemoglobin Kansas is less stable than
normal.
d. The presence ofless oxy-Hb in hemoglobin Kansas indicates this
type of Hb has alower affinity for oxygen.
e. The p50 forhemoglobin Kansas is higher than normal.
Answer:
The false statement is option a.
Explanation:
If there occurs a disruption of a hydrogen bond, which usually stabilizes the R-state of hemoglobin, there is not likely to be an elevation in the concentration of R-state due to the unsteadiness of the hydrogen bond. The R-state would either remain constant or will get slow down.
Thus, the statement, that is, in hemoglobin Kansas, there is an elevation in the concentration of R-state and a reduction in the concentration of T-state is false.
What would be the consequence to an organism if they are missing the following DNA repair mechanisms:
a. DNA polymerase proofreading
b. Mismatch repair enzymes
c. Nucleotide excision repair enzymes
Answer:
a. DNA polymerase proofreading: consequence of its absence is the DNA mutation
b. Mismatch repair enzymes : consequence of its absence impedes homologous recombination resulting in the final mutation
c. Nucleotide excision repair enzymes : the absence of nucleotide cleavage repair enzymes would impede the functioning of damaged DNA repair mechanisms
Explanation:
a. DNA polymerases are the enzymes that form the DNA in cells. During DNA replication (copying), most DNA polymerases can "check their work" with each base they add. This process is called review. If the polymerase detects that you have added a wrong nucleotide (incorrectly paired), remove it and replace it immediately, before continuing with DNA synthesis
b. In homologous recombination, the information from the homologous chromosome that matches that of the damaged one (or from a sister chromatid if the DNA has been copied) is used to repair the fragmentation. In this process the two homologous chromosomes are approached and the undamaged region of the homologue or the chromatide is used as a template to replace the damaged region of the broken chromosome. Homologous recombination is "cleaner" than the union of non-homologous ends and does not usually cause 11 mutations
c. Excision repair: damage to one or a few DNA bases is usually fixed by removing (excising) and replacing the damaged region. In repair by base cleavage, only the damaged base is removed. In nucleotide excision repair, as in the mating repair we saw earlier, a nucleotide section is removed
The absence of DNA repair mechanisms such as DNA polymerase proofreading, mismatch repair enzymes, and nucleotide excision repair enzymes can lead to an elevated mutation rate, causing genomic instability and increasing the risk of cancer and genetic disorders.
Consequences of Missing DNA Repair Mechanisms
The integrity of DNA is safeguarded by various repair mechanisms. When these systems fail or are absent, the stability and function of an organism's genome are compromised. Here's what happens when certain DNA repair mechanisms are missing:
DNA polymerase proofreading: DNA polymerase adds nucleotides during DNA replication and conducts proofreading to ensure accuracy. If proofreading is compromised, incorrect bases may be incorporated, resulting in mutations which can lead to cancers or other genetic disorders.
Mismatch repair enzymes: These enzymes correct errors that escape proofreading during replication. Without mismatch repair, these errors become permanent, increasing mutation rates and contributing to diseases like cancer.
Nucleotide excision repair enzymes: These enzymes repair bulky lesions such as thymine dimers which are primarily caused by UV light. Absence of these enzymes may lead to a higher incidence of skin cancer due to the accumulation of these lesions.
In summary, the lack of these DNA repair mechanisms can result in increased mutation rates, leading to genomic instability, and may significantly raise the risk of cancer and other hereditary diseases.
Which end of a new mRNA transcript gets a cap during processing in the nucleus?
a. the top
b. the bottom
c. the 3' end
d. the 5' end
Answer:
d. the 5' end
Explanation:
Capping is a co-transcriptional modification made to RNA in the nucleus after the first 25–30 nts are incorporated into the nascent transcript, which is synthetized in the 5' ---> 3' direction.
The cap consists of a methylated guanosine nucleotide added to the 5' end of the new mRNA transcript, and is important for several processes, which include:
Protection of the mRNA from the attack of phosphatases and nucleases.Splicing of mRNA in the nucleus.Nuclear export of the mRNA to the cytoplasm.Cap-dependent protein synthesis.What are the common promoter elements found in eukaryotic genes, and how are they different from enhancer elements?
Answer:
In eukaryotic cells you find core and proximal promoters.
Promotors are specific DNA sequences where transcription factors (proteins) and RNA polymerase binds to initiate transcription. Promotors are located upstream the coding sequence
Core promoters are where RNA polymersae binds and proximal promoters are where transcription factors bind.
Enhancer elements are DNA sequences where transcription factors (proteins) bind to increase the rate of expresion of an specific gene. Enhancers can be located either upstream, downstream or thousands of nucleotids away from the of the coding region.
Explanation:
Promoters and enhancer are key elements for controling gene regulation. Transcription begins when chromatin rearranges from a condensed state to a accesible state, this allow to transcrition factors and RNA polymerase to bind specif DNA sequences (promotors). Proteins bind to enhancers , this complex develops a DNA loop, so that the protein that is bound to the enhancer interacts with the RNA polymersase. When this interaction is made, the activity of the RNA polymerase is increased.
Define these terms: artery, arteriole, capillary bed, venule, and vein. Why do capillaries have sphincters?
Answer:
Artery: elastic vessels that carry blood away from the hearth at high pressures.Arteriole: subdivisions of arteries, they are thinner and have muscles that connect with the sympathetic nervous system. Capillary bed: it's a network of capillaries.Venule: Microscopic vessels that connect veins and capillaries.Vein: Blood vessels that carry blood back to the atria, they are less elastic than arteries.Capillaries are the smallest-diameter blood vessels that connect the smallest arterioles to the smallest venules, they have sphincters to control the blood distribution, based on the body's demands, the can relax or constrict so the blood can follow specific pathways to meet the tissue's necessities.
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The two major divisions of the nervous system are the __________
a. sympathetic and parasympathetic
b. mCNS and PNS
c. sensory and motor
d. voluntary and involuntary
Answer:
mCNS and PNS.
Explanation:
Nervous system of the body includes all the the nerves that carry message in the body from the spinal cord and brain . Nervous system has divided into two main branches.
The two main divisions of the nervous system are peripheral nervous system (PNS) and central nervous system (CNS). The central nervous system constitutes of the spinal cord and brain. The peripheral nervous system include the sensory receptor, motor nerves and sensory neurons.
Thus, the correct answer is option (b).
The two principal parts of the nervous system are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). The CNS is the main command system for the body, while the PNS is responsible for transmitting messages to various body parts.
Explanation:The two major divisions of the nervous system are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). The CNS includes the brain and spinal cord, and it is the primary command center for the body. The PNS includes all the nerves that branch out from the brain and spinal cord and extend to other parts of the body such as muscles and organs. These two divisions work together to transmit and process information to respond to stimuli from both internal and external environments.
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Why must reverse transcriptase be used to create a eukaryotic expression library?
a. reverse transcriptase is only used to create prokaryotic expression libraries
b. reverse transcriptase creates cDNA from mRNA in prokaryotes
c. reverse transcriptase ensures the gene is in the correct orientation within the expression vector to create protein
d. reverse transcriptase creates cDNA from mRNA because genes in eukaryotes have large numbers of non-coding regions.
e. no other enzymes are used to create expression libraries except restriction enzymes
Answer:
Option (d).
Explanation:
Genomic library may be defined as the total genome DNA of the organism. Reverse transcriptase is the enzyme used for the formation of DNA from the RNA molecule.
The eukaryotes DNA contain large number of sequences called introns that creates a problem in the construction of the eukaryote genomic library. This problem can be solved by creating the complementary DNA from the RNA molecule free from the introns.
Thus, the correct answer is option (d).